There is a need for preventing the buildup of ice and snow accumulation on vehicles which can impair the effectiveness of windshield wiper blades in cleaning the windshield of cold weather precipitation. Also, wintertime freeze-up and icing of windshield wiper blades causes the wiper blades to lose flexibility and not sweep the curved windshield found on most motor vehicles clear enough for good driving visibility.
U.S. Pat. No. 5,841,106 to Kohler, which is herein incorporated by reference, discloses a heated windshield wiper assembly which includes an external heating coil positioned next to the blade portion of the assembly. The heating coil's activation switch is in the interior of the vehicle and allows a user to selectively energize the external heating coil.
U.S. Pat. No. 5,603,856 discloses a windshield wiper having a shroud which encloses an electrically heated chamber which prevents ice and snow deposits on the shroud.
U.S. Pat. No. 3,532,561 which is herein incorporated by reference, discloses a vehicle windshield wiper assembly which contains a flexible heater wire disposed in and extending longitudinally throughout the body of a flexible wiper blade. A switch means is connected to a power source of the vehicle for activating the heating element is manually operated by the user.
U.S. Pat. No. 5,787,543 to Selders et al, which is herein incorporated by reference, discloses a windshield wiper blade having an internal conduit extending throughout the length through which a flexible spiral heating element is placed. The heating element is coupled to power source which is activated by the user.
In another approach, the windshield wiper frame and flexible linkages are enclosed in a heated envelope (U.S. Pat. Nos. 3,523,626 and 3,619,556). In U.S. Pat. No. 3,523,626, the envelope is filled with a heated fluid. These designs are meant to heat the frame and linkages to remove ice and snow which interfere with the movement of the frame and linkages. These heated envelopes are cumbersome and impede flexing action. In these indirect heating methods, electrical energy is used ineffectively and inefficiently in an attempt to improve the wiping action.
In summary, the foregoing prior art has not solved the problem of providing satisfactory wiping performance in frigid snowy and icy conditions while simultaneously removing and keeping the wiper blade, frame and linkages free from interference by ice and snow.